As a measure for enabling emergency running at the time when a pneumatic tire is punctured during the running of a vehicle, many measures have heretofore been known, in which a core-type run-flat supporting body is inserted into a cavity of a pneumatic tire, and thus supports an applied load.
Among such core-type run-flat support bodies, in particular, there is a run-flat supporting body, in which a main body is composed of an annular shell whose cross section in a tire width direction bifurcates into right and left leg portions, and in which elastic rings are attached to both of the leg portions for supporting the run-flat supporting body on a rim seat. Such a run-flat supporting body can be employed to the existing wheel as it is without adding a structural modification thereto. Accordingly, it is expected that use will be made of the run-flat supporting body described above in the future.
The above-described run-flat supporting body has had an advantage that previously attaching the run-flat supporting body to the wheel ensures safe running of the vehicle at the time when the tire is punctured. On the contrary, the run-flat supporting body has also had a disadvantageous point that the attachment thereof causes a deterioration of fuel economy since the attachment brings a weight increase of the vehicle.
As a countermeasure against the disadvantage, there is a proposal to achieve a weight reduction of the run-flat supporting body by providing a large number of through holes in the annular shell (refer to Patent Document 1).
Specifically, not only does such provision of the through holes contribute to the weight reduction, but also it allows the air to flow between the inside and outside of the annular shell. This makes it possible to appropriately maintain temperature distribution in the cavity of the tire during the running. The provision of the through holes thus can contribute to the safe running, and is preferable from the perspective of this point.
Patent Document 1: Japanese Patent Application Kokai publication No. 2004-51088